An Israeli soldier prays next to an army vehicle near the border between Israel and the Gaza StripPhoto: AP

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Photo: AFP/Getty

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Israeli strike on UN-run school in Gaza kills 30Photo: REUTERS

By Andrew Wander in Beirut

1:40PM GMT 08 Jan 2009

Three Katyusha rockets landed in the Nahariya area of Israel, slightly wounding two people. The Israeli army immediately struck back, firing five artillery rounds across the border into the town of Tair Harfa. No casualties were reported.

This relatively low-key response, described as "pinpoint" and targeted on the "source of the fire", indicates that Israel has no desire to escalate the situation.

Fouad Siniora, the Lebanese prime minister, sought to ease the tension by condemning the attack on his neighbour, saying it was the work of "parties who stand to lose from the continued stability in Lebanon and want to drag it to a situation it does not want and which serves the Israeli plan and does not serve Lebanon's interests nor the Palestinian or Arab interests."

But tensions are running high in the border region. Schools are closed, and the United Nations peacekeeping force in Lebanon, Unifil, has stepped up patrols along the frontier. Israeli jets were reported to have broken the sound barrier over southern Lebanon in the hours after the attacks.

Since Israel launched its operation in the Gaza Strip, there have been fears that guerrillas based in Lebanon could retaliate by opening a second front in the north.

Of particular concern is a potential war between Israel and Hizbollah, the radical Shia group, which would have devastating consequences.

Israel believes that Hizbollah has amassed an arsenal of about 40,000 missiles and accuses Iran of supplying the weapons. In the event of war, Israeli officials have pledged to launch an even more intense version of their assault on Lebanon in 2006 which claimed over 1,200 lives.

But Lebanese security sources said that they did not believe Hizbollah carried out this attack. Instead, the Popular Front for the Liberation of Palestine – General Command (PFLP-GC), a Marxist guerrilla group, may have been responsible.

PLFP-GC has pointedly refused to deny carrying out the attack. Observers agree that Palestinian groups are more likely to be behind the attacks than Hizbollah. Amal Saad Ghoreyeb, a commentator in Lebanon's capital, Beirut, and the author of a book on Hizbollah, said that the Shia group saw no need to intervene in the Gaza conflict.

"Hizbollah is optimistic about Hamas's performance," she said. "Hamas has been trained by Hizbollah and Iran, but they jealously guard their autonomy. If Hizbollah were to step in for Hamas, what would that say about them?"

An election is approaching in Lebanon and domestic politics helps explain why Hizbollah may choose to stay out. "Hizbollah and its allies have a good chance of winning the elections in June," said Ms Ghoreyeb. "That would be a strategic blow to Israel and the US. Why would they want to jeopardise that position?"

But Hizbollah's apparent restraint may not be indefinite. "If Hamas is on the verge of collapse, Hizbollah will act. I'm certain that Hizbollah would see it as its duty to help Hamas in that situation," said Ms Ghoreyeb.

Hizbollah is believed to have privately assured Lebanon's government that it remains committed to the ceasefire that ended the 2006 war with Israel. But its rhetoric has hardened recently. Hassan Nasrallah, the Hizbollah leader, spoke on Wednesday about the potential for war with Israel, saying that "all possibilities were open", adding: "Your jets will not frighten us, and your threats will not frighten us. We are ready for any aggression."